GOETHITE
goethite, gothite
(noun) a red or yellow or brown mineral; an oxide of iron that is a common constituent of rust
Source: WordNet® 3.1
Etymology
Noun
goethite (countable and uncountable, plural goethites)
(mineral) An iron oxyhydroxide that is the main constituent of rust.
Source: Wiktionary
Gö"thite, or Goe"thite (, n. Etym: [After the poet Göthe.] (Min.)
Definition: A hydrous oxide of iron, occurring in prismatic crystals, also
massive, with a fibrous, reniform, or stalactitic structure. The
color varies from yellowish to blackish brown.
Source: Webster’s Unabridged Dictionary 1913 Edition